Abstract

Although this child initially appeared to be a typical case of congenital LLD, it became apparent that with dysfunction of all the right lower extremity growth plates, a massive LLD would ensue. The LLD was a coming from both femur and tibia. Our plan after the initial femur lengthening was to do a lengthening of the tibia/fibula and then to come back and repeat a femur lengthening. Also planned was an epiphysiodesis of the contralateral side to prevent additional LLD after the last lengthening at age 15.

The growth plate shutdown and dysplasia were not well defined despite additional consultation with several pediatric orthopedic colleagues and a geneticist. The main practical issue of LLD was, however, addressed with three well timed lengthenings and an epiphysiodesis of the long side. This case illustrates an excellent functional and aesthetic outcome following 20 cm (8 inches) of limb lengthening in 3 stages. Adjuvant procedures including epiphsiodesis, quadricepsplasty, and gastrocnemius recession were all used to achieve limb salvage in this child.

Brief Clinical History:

J.S. presented to us at age 9 years with a 5.5 cm LLD (Figures 1,2). There was no history of infection or trauma and growth plates looked normal on x-ray. This appeared to be a congenital LLD and the predicted LLD at maturity was thought to be 7.5 cm using standard prediction methods. He underwent a right femur lengthening of 5 cm using a monolateral frame on the femur (Figures 3,4). A minimal incision quadricepsplasty was done to treat a knee extension contracture (40 degrees) with an excellent functional result (Figure 5). This was uneventful and we planned to do another small lengthening as a young teenager.

However, during follow up, the growth plates were noted to be increasingly irregular. At age 12 years, the patient was noted to have 7 cm of additional LLD and trochanteric overgrowth at the hip (Figure 6). The radiographs now demonstrated abnormal closure of all growth plates of the right lower extremity including the proximal and distal femur as well as the proximal and distal tibia. A poorly defined dysplasia affecting the growth plates was apparent. At age 12 years, he underwent a 7 cm lengthening of the tibia and fibula using an Ilizarov/ Taylor spatial frame (TSF) (Figure 7). Gastrocnemius recession was done to treat an equinus contracture of 20 degrees. Closure of the proximal femur trochanteric growth plate was also done to prevent progression of hip deformity. This resulted in equal leg lengths at age 13 (Figure 8).

At age 15 years, he had an additional 8 cm of LLD. At that time, he underwent right femur lengthening over a nail (LON) to gain 8 cm and achieve equal leg lengths (Figure 9). A contralateral left distal femur and proximal tibia epiphysiodesis was also performed to prevent additional LLD. In total, he underwent 20 cm of right lower extremity lengthening in 3 stages (Figure 10). The patient is now 21 years of age and has equal leg lengths, a normal gait, and normal hip, knee, and ankle range of motion. He has no functional limitations.

Preoperative Clinical Photos and Radiographs:

Preoperative Problem List

Unilateral lower extremity growth plate shutdown

Massive predicted LLD

Varus deformity of hip

Good condition of hip, knee, ankle, foot and no interest from family in amputation and prosthetic fitting

Extension contracture of knee after first femur lengthening

Equinus contracture of the ankle after tibia/ fibula lengthening

Treatment Strategy

Our plan after the initial femur lengthening was to do a lengthening of the tibia/fibula and then to come back and repeat a femur lengthening. Also planned was an epiphysiodesis of the contralateral side to prevent additional LLD after the last lengthening at age 15.

Basic Principles

Initially with a presumed diagnosis of congenital LLD, the predicted LLD was 7.5 cm using the multiplier method. Once it became apparent that the diagnosis was not a typical congenital case but rather that there was growth plate dysfunction, we made calculations using the growth remaining component of the multiplier method. Practically speaking, we tried to keep up with the progressive LLD by performing 3 staged lengthenings staggering the long bones of the lower extremity (femur-tibia-femur) followed by an epiphysiodesis of the distal femur/proximal tibia. Soft-tissue contractures were treated with soft-tissue releases. During the first femur lengthening and during the tibial lengthening, soft tissue contractures developed that were recalcitrant to physical therapy.

Our minimal incision quadricepsplasty was effective in treating the knee extension contracture at the end of femur distraction. Gastrocnemius recession was used to treat the ankle equinus contracture during the tibial lengthening. Well-timed soft tissue releases have been very effective in our practice to preserve normal joint range of motion. Varus deformity of the hip was addressed with epiphysiodesis of the greater trochanter in growing child as part of a guided growth approach.

Images During Treatment:

Figures 3,4: After 5 cm of femur lengthening using a monolateral frame (just before frame removal)

Figures 9A,B: At age 15, during an 8 cm femur lengthening using LON technique

Technical Pearls:

The second lengthening at age 15 was done using LON. This is a hybrid technique in which the femur is lengthened over an IM nail with an external fixator. There is no contact between internal and external fixation in order to avoid infection and impingement between rod and external fixation pins which could cause failure of the lengthening to progress. The external fixator pins were placed posterior and distal to the IM nail. At the end of distraction which was 3 months in this case, the IM rod was locked and the fixator was removed. This technique has been very effective for decreasing the time in external fixation and preventing fracture.

Outcome clinical photos and radiographs:

Avoiding and Managing Problems

Extension contracture of the knee during femur lengthening that is not responsive to physiotherapy can be managed with a mini-quadricepsplasty. Equinus contracture of the ankle that is not responsive to physiotherapy can be managed with a gastrocsoleus recession.